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Specification `of Letters llxatentpl'o.4 9,526, dated January 4 1853.

To all 'whom t may concern.'

Be it Vknown that I, RUDOLPH rKmi'rnR-of the city and county of New York `andState of New York, have invented certain new and useful Improvements in Machinery for Covering the Hammers of Pianofortes; and I do hereby declare that the following is a full, clear, and eXact description of the same, reference being made to the annexeddrawings, making a part of this specifica tion, in which-f Figure I is a side view; Fig. III a top, View; Fig. III an end view; Fig.V IV a longitudinal vertical sect-ion; Fig. V atranS- verse sect-ion; Figs. VI, VII and VIII," are parts in detail, and similar letters refer to similar parts throughout.

In the manufacture of pianofortes one of the most delicate, difficult and tedious parts is the covering of the hammers. Few workmen comparatively attain excellence ,in this department. The requisites in a goodset of hammers are that they should have regularv graduations of thickness, hardness and weight, the greatest hardness, least thick* nessand weight at the highest partvofthe scale or treble; and vincreasimg from note to note with a regular andequal succession to the lowest. The covering material is applied with glue, and, as in the old mode, each hammer is done separately by hand, the workman has no guide to the obtaining of the above requisite except his: skill. Hence there are always many condemned hammers which have to be replaced on the trial of'them by the regulator ofthe instrument.

My invention has for its object thecovering of the hammers in a connected set; the several thicknesses or coats being. applied one after the other but to the whole sety at once. My machine produces perfect regularity in the graduations of hardness` of. the hammer and this is effected by the degree of tension with which the felt is stretched over the piece of wood called the hammer head and may be adjusted and graduated from end to end as desired. It insures the perfect gluing of all parts of the surface supplied with that material; it effects alarge saving in material and time besides producing a superior tone in the instrument, for there are no, unequal or false notes, since there is vno irregularity in the rate 01' degree ofrhardness in thehammers.

vficient number of pieces to form aset.

In-'using'my mach-incl proposeto employ felt the, coveringwmaterial. ForY this i pur-py pose nthe article is manufactured in sheet-sof adwidthriequal to the length of the strip required and ofunequal thickness, ,one edge being twice or` three times the thickness of the other edge, the thickness diminishing.

by argradual taper.4 The hammer heads are formed" out ofa wedge like strip of wood, being-thickerat one end than theother, the strip beinglong enough to be cut into asuff In sawing, the heads out each is numbered, `so ascto insure the same relation that they had inthe strip. This is necessary because the bass hammers are heavier than the treble.

The coveringconsists of threethicknesses at the base, gradually taperingto two to- -wardthe middle, and continuing doubleto the end, To prepare the covering a narrow stripv proper for the innermost coat" is cut from a sheet of felt prepared as described, and ofv suflicient length to cover asmany hammer headsas required, say for one-third from the base lup this is then shaved down alongjeach of its edges to a feather, leaving thevthickest partin themiddle, as seen by the cross section in Fig. VI of'details, at (a). The neXt coat is prepared in like manner, butextending to the whole length requiredi-to form the set, and lastly the third coat.

Tocover thehammers byy my machine: First the several distinct pieces composingV thejset of hammer heads are to he arranged in their proper order in a clamp. This is a strong bar- A consistingof two pieces., or plates, whichare attachedparallel to each other by bolts and nuts. One plate is flangedfat thetop edge andthe two ,ends tel'- minate indovetails to t a dovetail groove in the upright guides asrseenat (c) Fig.` II; This. clamp extends acrossthetop ofthe machine, as. sho-wn, and fits in a dovetail formed in the topof two uprights,`w'her e it is permanently keyed. Theuprightsthemselvesare 4made so as to slide up and down andindoing so carry withthem the clamp in a mannerto be described. The clamp A' Vmust be taken out of the machine to fit the hammer heads are then arranged in this space in the order of their numbers, as seen at (e) and fullsize at Figs. VI and VII. The nuts are then screwed hard up and the hammer heads firmly clamped between the plates ready to be introduced upon the machine. The next operation is to placeY the prepared felt for -t-he covering upon the machine; The parts intended to effect this operation consist of a frame or carriage which slides down between the lips of a vise the jaws of' which are at first kept closed by a series O springs which yield to receive the ends ot' the hammer heads but are afterward capable of being rigidly fixed upon any object between them by screws. lVhen this sliding frame descends it carries along with it the hammer heads in the clamp, the pointsof said hammer heads resting upon the strips of felt as seen at (a, 5,) in Fig. VI, so that on being forced down the jaws part andl effect the bending up of the felt upon the sides of the hammer heads, as seen in Fig. VII. At B is a narrow block extending from one end of the frame to the other, and guided in its movements up and down by the upright pieces C. Upon its top edge there is a groove cut longitudinally from one end to the other as seen at (g) Figs. IV and V, within which groove is a series of pullies (g). lIhe groove is covered by a plate on which rests a series of shortlevers (it) one end of each lever is forked so as to receive a small pulley (/L) as shown. All the levers are acted upon simultaneously by means of a cord (z') weighted at one end, and rove through the two sets of pulleys (g and L). One end of each lever z) supports a long narrow bar (7c) extending from one end to the other of the machine. rlhe top edge of (/c) is perfectly straight in the direction of its length, but has a slight hollow cut in it, as seen more clearly in the enlarged section Figs. VI, VII. The underside terminates in a row of legs spaced so that each leg shall rest upon one end of a lever (71,), as shown. It will now be seen that the object of the levers and cord and weight are for the purpose of keeping the top edge of the bar (7c) pressing hard against the points of the hammer heads (e). Thus the strips of felt (a, 6,) on being laid upon the hollow in this bar, and the clamp A containing the hammer heads being pressed down so as to bring their edges upon the felt, t-he latter will be held rmly between the two, viz, the top of the bar (7c) and the ends of the hammer heads. The degree of pressure to be applied to this part is regulated by the weight or a spring or'other power may be substituted. The bar (7e) is kept in its vertical position by means of a number of braces consisting ot thin strips of metal or other material, which extend down parallel to each leg and follow the sides of B, passing around under its bottom edge and up the other side to the bar again, as seen at (0) Figs. IV and V, partly in dotted lines. At (m) is a narrow bar which rests upon the bed of the machine; a slight sliding motion may be given to it by means of a rod (m). At (MW) are two studs carried by the bar, the tops of which may be brought to coincide with two other studs (0'), depending from the lower edge of B. Thus when (m) is kmade to coincide with (0) they form pillars upon which B may be supported by the bed of the machine, and when not so situated, but placed as in the drawings, B may be permitted to j descend.

The clamp A with its hammer heads, bar (74), the piece B with its rollers, levers, &c. when fixed in cert-ain positions, are capable of being moved connectedly in an unaltered position up and down between the main upright C of the machine. To effect this all those pieces are attached to two guide frames which may be permitted to slide in guides attached to the upright C. These two'frames are seen at (p), and (p) are `the gibs or grooves attached to C for the frames to slide in; (22) are nuts attached to (p) to elevate and lower that by the screws and cranks (CW) as shown. The form of the frame is seen detached from the machine at Fig. VIII. In the upper part is a slot dovetailed on the sides, as seen at Fig. II. This receives the ends of the clamp A, which when put in are firmly held in place by keys (dm). The lower part forms a strap within whichthe block B rests, the opening being greater than the width of the block so that the latter may have some play within it, and at (pm) is a screw Vby which B may be raised or lowered as far as permitted by the length of the strap. Suppose that A, (lo), B, were out of the machine; then by turning the cranks (cZ) the frame (p) would be raisedV or lowered. Now place B in the strap, the lower edge resting upon the screws (pm) then it is evident that B may be raised or lowered by the action of said screws. If (7c) is now put in it will be raised or lowered by raising or lowering B by (pm). Unscrew (pm)r until B rests upon the bottom of the strap. Now fix A with its row of hammer heads in the frame and key it with the keys (dm) so that it is firmly seated in place; there will then be a space between the lower edge of (e) and the top or hollowed edge of the rail (7c). Lay upon the two strips (a, 5,) of felt, then turn the screws (pm) and raise B; this carries up the levers (72.) on which rests (7c), and consequently that is carried up until the strips of felt are brought to bear against the edges of the hammer heads (e) continue to screw up (pm) and the levers will begin to tilt, causing the cord to be stretched and thereby raise the weight (71').

Thus every part of the hollow on (7c) is pressed up equally against the felt, and that against the ends of the hammer heads with a power according to the weight of (2). This pressure produces a good fit on the end of the hammer and properly shapes it as seen in Fig. VI. The glue is now to be applied to the ends of the felt and along the sides of the hammer heads as the latter lies spread out upon the mouth piece of the vise, as seen more plainly in Fig. VI at (a, b). As soon as this is done, the two cranks (cZ) are turned around and the tw'o pieces (p) are made to descend carrying with them in the relative positions just described, A (le) B; the piece (la) slipping from between the lips of the vise, while the hammer heads follow, and the lips pressing up the glued sides of the felt against the sides of the hammer heads until they come into the positions shown in Fig. VII. After the ,gluing has been completed the frame (p) is raised, lifting the hammers out from between the jaws of the vise, which is attached to the per manent frame as hereafter described, the piece is then moved so that (0') rest-s upon (m) and there supports B. The points of the screws (pm) are now taken from under B or screwed down as far as they will go; this operation permits the frame (79) to be still further carried up without taking B with it, and as the clamp A is Xed to the top of (29) this effects the clearing of the ends of the hammers from (7a), when the keys (CZH) being removed the clamp can be taken out and a fresh set of hammer heads introduced to be acted on as before.

This brings me to the construction and o eration of the second art, viz, the vise. Tie jaws are formed of? bars placed vertically at a little distance apart and parallel to each other, as seen at (r). Below the lip pieces they are bent outward so as to allow the block B to play between, as seen in Fig. V. The several pieces (1') are fastened at the bottom to a continuous strip (r) and at the upper part they are connected together by another piece (7) let in on the inside face of the ends. vThis piece should be of metal as it is by this the bite or grip is given upon the lips. The lips (s) are right angled strips' and should be of metal; these lie within and rest upon the top corner of the jaws formed by (1), as shown in the several figures and more clearly in the enlarged view at Figs. VI and VII. It will be observed that these inside faces which embrace the plate (7c) are slightly angled. This is for the purpose of embracing the felt after the head of the hammer has been pushed through and producing Aan equal pressure upon the sides of the hammer heads, or along all that part where the glue has been applied (no .glue being .put upon the point or extreme end, as that would injure the elasticity of the felt). This operation is more particularly shown in Fig. VII. Upon the horizontal angle of the lip pieces are laid two other pieces which may be of wood, as seen at (s), having the inside surfaces beveled as shown in Fig. VI. These form the gluing tables, and support the edges of the felt while the brush and glue are applied, as clearly seen. They can be taken off to be cleaned whenever the waste glue accumulates sufficient-ly to require it. In the first part it was stated that while the set of hammer heads and the strips of felt were being carried down between the lips of the vise, the jaws of the latter were all the time pressing hard upon the felt to secure the proper contact of the felt with the hammer hea-ds and thus insure the perfect gluing of the parts. This is effected by a series of levers and springs arranged as follows: Along the sides of the jaws of the vise, but so as to leave a narrow space between the two, are arranged a number of vertical posts (t). The lower ends of these are framed in t-he pieces (r), the tops being strongly braced together by the strips (t). This outside frame forms a kind of secondary vise, as it also may be sprung together a short distance, the pieces Fig. V forming the lips which press against the top of the jaws (r). This pressure is produced by acting upon the nuts (u) to a row of bolts (u) which pass through from side to side in holes made in the piece (t). Between the several posts (t), are a system of levers (o) having their fulcra in the upper end of the frame (t). The weight or lforce acting upon the levers consists of a series of springs (w). These may be, and as repre sented are, bands of rubber rove thro-ugh and looped into pegs formed upon the bottom of each lever by sawing out several slots, as clearly shown at (w) Fig. I. These bands pass through slots cut in the lower ends of the pieces (fr) forming the jaws of the vise, so that t-he latter shall interpose no obstacle to their free working.

The power or pressure is applied at a central support This is a projecting rib eX- tending along the whole of'the levers and secured to a flat piece or flange which restsagainst and bears upon the uprights (1), forming the jaws of the vise. A side view is given in dotted lines in the sectional Fig. IV and an end view in Fig. V. Now it will be seenthat the springs (fw) drawingupon the ends of the levers (o) whose fulcra is (t) 4will press upon the pieces (w) and thus' again press upon the uprights (r) forming the jaws of the vise and therefore press the lips (s) together as before described. Hence as the bar (7c) descends followed by (e), holding between them the felt (a, b), the latter by the pressure of (s) must be bent up and kept hard pressed against the sides of (e). The degree of pressure produced by the springs may be increased or diminished by shift-ing the place of along the levers (o), to increase, the pressure must be brought toward the fulcrum and vice Versa. This is accomplished by supporting (00) upon a second piece (y) the upper edge of which is cut to form several inclined planes (g/), the piece (of) also being notched to lit as seen at (g/). A pawl and ratchet regulates the several heights to which the bar (x) is to be raised. The bar (m) and (az) can only play up and down, while may move laterally or at right angles to (w) and is supported upon studs (g/). The ratchet is at (e) and the pawl at (2') attached to (90). To move in order to raise draw the rod (am) until the end of the pawl (2') falls into the iirst notch (a), this causes to slide up the plane or angle (g/), thus is elevated to any position desired. To lower raise the pawl (z) which can be done by a small rod (2) reaching to the to-p of the machine and thus withdraw (y) to the point desired. After the hammer heads (e) and the felthave been pressed between the jaws of the vise in t-he manner before described, and as shown in Fig. VII, the pressure must be increased upon the felt to a greater degree than that produced by the action of the springs (w) and levers (o). This is accomplished by tightening the nut (w) upon the bolts (u), which action springs the outer frame toward the center and brings the pieces (t) to bear against the top o-f (1), and the jaws and lips (s) are clamped upon (e) with any pressure desired. This pressure is maintained until t-he glue has fully set or become hard enough to allow of the removal of the hammers. As soon as the pressure is finally given by the screws and bolts (u, u), the pressure upon the end of the felt produced by the hollow in the plate (7s) must be taken off, because if it were maintained it would mar the hammer and unduly harden it. To accomplish this it is only necessary to lower B by means of the screw (pm) as before described, and as (7c) rests upon B through the intervention of the levers (h) that accordingly descends also leaving A and (e) stationary in the jaws of the vise, and therefore all clear. In order to avoid the necessity of working the screws (pm) the distance required for the movement of B, I shorten the operation by resting B upon blocks B so that by loosening the screws a little the block may be withdrawn and B will descend the distance required, the studs (MW) being removed from under (0). After the glue has become hard the hammers are removed. To do this all the pressure must be taken ofi".

The screws (u) are first loosened to relieve the outside clamp (t). The spring pressure upon the jaws must also be taken off, so as to allow the hammers to slip from between the lips without obstruction, as otherwise there would be a risk of having the felt torn ofi'l again. The lower ends of the levers drop into a groove (am) formed in a table running the whole length of the machine, this table rests partly upon brackets outside and partly upon the bed of the frame itself. A slight horizontal play may be imparted to it, as shown by the dotted lines in Fig. III, and where also a space is cut out of the brackets to allow it, the levers must be spread apart by pushing out these grooves (z), which when done takes the pressure off of the rib (w) and therefore from the jaws also. This .is done by means of several small toggles (j) seen in Fig. II one end of each of these rests in a sliding bar (53) and the other end acts against the back part of the shelf in which the groove (zm) is situated. The bars (7W) are coupled to a lever and treadle on the outside of the machine at F. By pressing down the treadle as seen in Fig. I the two bars (7W) will be drawn along, this will straighten the toggles (j) Fig. II and push out the groove (zm) carrying with it the ends of the lever and thus relieve the pressure on the jaws (r). The twohandles (Z) must now be turned to raise up the frame (p) and all the pieces depending upon its movements until the two studs (0) are sufficiently high to allow the studs (m) to go under. hammers will then be lifted out clear of the jaws, the top of (7c) will be in place to receive the next strips of felt for additional coats; if no others are to be applied then the clamp A may be removed for taking out the finished hammers and receive a new set of hammer heads. The strips of felt are now laid on as before, the clamp A must be lowered to bring the edges of the hammer heads to press on the felt. This is done by turning the handles (cZ) again, which lowers the frame (p), the block B remains stationary, resting upon the studs (0 m) by which means the grooved top of (7o) is maintained just above the mouth of the vise as shown in the several gures. The points of the hammer heads (e) are again pressed upon the felt as before. The two screws (pm) are now to be brought to bear against B in order to keep (7c) pressed against (e), (the felt being between), this done the glue is to be applied as before described, the posts (m) withdrawn, the pressure of the springs applied to the jaws of the vise, the slides (p) made to descend carrying the felt (a, 5,) and point of the hammer heads (6') between the lip pieces, and t-he operation completed as before set forth.

What I claim as of my own invention, and

The

desire to secure by Letters Patent of the United States, is-

l. The application of the felt or other covering material to the whole set of hammer heads at one operation in the manner described.

2. I claim the clamp A, bar (le), levers, pulleys, and block B with the sliding frame (p) in combination substantially as described, but without limit-ing myself to the precise shapes and proportions or positions of the said parts, provided the arrangement embrace the means of holding the set of hammer heads and of bringing them to bear upon a table containing the strips of felt described and also the holding and moving the whole together either horizontally or vertically to and from the jaws of the vise as set forth.

3. I claim the vise in combination with and inclosing the bar and block B as described.

4. I claim the lip pieces in combination with said vise for the purpose described.

5. I claim the levers and springs in oombination with the vise for producing the pressure upon t-he sides of the felt during the passage of the hammer heads between the jaws of the vise as described.

6. II claim the method of increasing or diminishing the pressure of the levers upon the vise by means of the movable bridge in combination with the press and y) as described.

The whole being constructed and operating substantially in the manner described.

RUDOLPH KRETER.

Witnesses:

HENRY NUNNs, S. H. MAYNARD. 

